Genetic prediction of 33 blood group phenotypes using an existing genotype dataset

BACKGROUND

Accurate blood type data are essential for blood bank management, but due to costs, few of 43 blood group systems are routinely determined in Danish blood banks. However, a more comprehensive dataset of blood types is useful in scenarios such as rare blood type allocation. We aimed to investigate the viability and accuracy of predicting blood types by leveraging an existing dataset of imputed genotypes for two cohorts of approximately 90,000 each (Danish Blood Donor Study and Copenhagen Biobank) and present a more comprehensive overview of blood types for our Danish donor cohort.

STUDY DESIGN AND METHODS

Blood types were predicted from genome array data using known variant determinants. Prediction accuracy was confirmed by comparing with preexisting serological blood types. The Vel blood group was used to test the viability of using genetic prediction to narrow down the list of candidate donors with rare blood types.

RESULTS

Predicted phenotypes showed a high balanced accuracy >99.5% in most cases: A, B, C/c, Coa /Cob , Doa /Dob , E/e, Jka /Jkb , Kna /Knb , Kpa /Kpb , M/N, S/s, Sda , Se, and Yta /Ytb , while some performed slightly worse: Fya /Fyb , K/k, Lua /Lub , and Vel ~99%-98% and CW and P1 ~96%. Genetic prediction identified 70 potential Vel negatives in our cohort, 64 of whom were confirmed correct using polymerase chain reaction (negative predictive value: 91.5%).

DISCUSSION

High genetic prediction accuracy in most blood groups demonstrated the viability of generating blood types using preexisting genotype data at no cost and successfully narrowed the pool of potential individuals with the rare Vel-negative phenotype from 180,000 to 70.

Extended red blood cell antigens and phenotypes in Burkina Faso: potential issues to design local population-sourced red blood cell reagent panels

To date, 43 blood group systems with 349 red blood cell (RBC) antigens have been recognized. The study of their distribution is useful for blood services to improve their supply strategies for providing blood of rare phenotypes, but also to design indigenous RBC panels for alloantibody screening and identification. In Burkina Faso, the distribution of extended blood group antigens is not known. This study aimed to investigate the extended profiles of blood group antigens and phenotypes of this population and to raise limitations and potential strategies for the design of local RBC panels. We conducted a cross-sectional study that included group O blood donors. Extended phenotyping for antigens in the Rh, Kell, Kidd, Duffy, Lewis, MNS, and P1PK systems was performed using the conventional serologic tube technique. The prevalence of each antigen and phenotype combination was determined. A total of 763 blood donors were included. The majority were positive for D, c, e, and k and negative for Fy^a and Fy^b. The prevalence of K, Fy^a, Fy^b, and C^w was less than 5 percent. The most frequent Rh phenotype was Dce, and the most common probable haplotype was R₀R₀ (69.5%). For the other blood group systems, the K-k+ (99.4%), M+N+S+s- (43.4%), and Fy(a-b-) (98.8%) phenotypes were the most frequent. Antigenic polymorphism of blood group systems by ethnicity and geography argues for the design and evaluation of population-sourced RBC panels to meet specific antibody profiles. However, some of the specificities identified in our study, such as the rarity of double-dose antigen profiles for certain antigens and the cost of antigen phenotyping tests, are major challenges to overcome.

Generation of 'designer erythroblasts' lacking one or more blood group systems from CRISPR/Cas9 gene-edited human-induced pluripotent stem cells

Despite the recent advancements in transfusion medicine, red blood cell (RBC) alloimmunization remains a challenge for multiparous women and chronically transfused patients. At times, diagnostic laboratories depend on difficult-to-procure rare reagent RBCs for the identification of different alloantibodies in such subjects. We have addressed this issue by developing erythroblasts with custom phenotypes (Rh null, GPB null and Kx null/Kell low) using CRISPR/Cas9 gene-editing of a human induced pluripotent stem cell (hiPSC) parent line (OT1-1) for the blood group system genes: RHAG, GYPB and XK. Guide RNAs were cloned into Cas9-puromycin expression vector and transfected into OT1-1. Genotyping was performed to select puromycin-resistant hiPSC KOs. CRISPR/Cas9 gene-editing resulted in the successful generation of three KO lines, RHAG KO, GYPB KO and XK KO. The OT1-1 cell line, as well as the three KO hiPSC lines, were differentiated into CD34+ CD41+ CD235ab+ hematopoietic progenitor cells (HPCs) and subsequently to erythroblasts. Native OT1-1 erythroblasts were positive for the expression of Rh, MNS, Kell and H blood group systems. Differentiation of RHAG KO, GYPB KO and XK KO resulted in the formation of Rh null, GPB null and Kx null/Kell low erythroblasts, respectively. OT1-1 as well as the three KO erythroblasts remained positive for RBC markers-CD71 and BAND3. Erythroblasts were mostly at the polychromatic/ orthochromatic stage of differentiation. Up to ~400-fold increase in erythroblasts derived from HPCs was observed. The availability of custom erythroblasts generated from CRISPR/Cas9 gene-edited hiPSC should be a useful addition to the tools currently used for the detection of clinically important red cell alloantibodies.

Molecular genotyping of clinically important blood group antigens in patients with thalassaemia

Background & objectives:

In multitransfused thalassaemic patients, haemagglutination fails to phenotype the patient's blood group antigens due to the presence of donor-derived erythrocytes. DNA-based methods can overcome the limitations of haemagglutination and can be used to determine the correct antigen profile of these patients. This will facilitate the procurement of antigen-matched blood for transfusion to multitransfused patients. Thus, the aim of this study was to compare the serological phenotyping of common and clinically important antigens of Rh, Duffy, Kell, Kidd and MNS blood group systems with molecular genotyping amongst multitransfused thalassaemic patients.

Methods:

Blood samples from 200 patients with thalassaemia and 100 ‘O’ group regular blood donors were tested using standard serological techniques and polymerase chain reaction-based methods for common antigens/alleles (C, c, D, E, e, Fy^a, Fy^b, Jk^a, Jk^b, K, k, M, N, S, s).

Results:

Genotyping and phenotyping results were discordant in 77 per cent of thalassaemic patients for five pairs of antithetical antigens of Rh, Duffy, Kell and Kidd blood group systems. In the MNS blood group system, 59.1 per cent of patients showed discrepancy. The rate of alloimmunization among thalassaemics was 7.5 per cent.

Interpretation & conclusions:

Molecular genotyping enabled the determination of the actual antigen profile in multitransfused thalassaemia patients. This would help reduce the problem of alloimmunization in such patients and would also aid in the better management of transfusion therapy.

Phenotype frequencies of Rh (C, c, E, e), M, Mia and Kidd blood group systems among ethnic Thai blood donors from the north-east of Thailand

We here report the first study of antigen and phenotype frequencies of Rh (C, c, E, e), M, Mi^a and Kidd antigens in north-east Thai blood donors. Blood transfusion services aim to ensure availability of adequate and safe blood to minimize the development of transfusion reactions. For pre-transfusion testing, the most important blood group systems are ABO and RhD. The transfusion of ABO-compatible otherwise unknown phenotype blood may result in alloimmunization, especially in multi-transfused patients. Extended red blood cell (RBC) phenotyping and selection of blood negative for specific antigens reduce post-transfusion complications and allow for effective blood transfusion regimens to be achieved. A total of 13,567 regular repeated, voluntary Thai blood donors were included for red-cell antigen typing of Rh (D, C, E, c, e). Samples from 12,768, 9,389 and 13,059 donors were typed for Kidd, M and Mi^a antigens, respectively. Amongst Rh antigens, e was the most common (96.80%) followed by C (95.50%), c (34.40%) and E (32.20%) with CCDee (60.00%) being the most common phenotype. For Kidd phenotypes, Jk(a+b+) was the most common (46.73%) and Jk(a-b-) was rare (0.07%). For the M and Mi^a antigen, M(+) was most frequently found (94.96%) and Mi^a (+) was found in 17.97% of individuals. Knowledge of red-cell antigen phenotype frequencies in a population is helpful for creating a phenotype database of blood donors which can provide antigen-negative compatible blood to patients with multiple alloantibodies. Moreover, provision of antigen-matched blood can prevent alloimmunization in multi-transfused patients.

CMAH genotyping survey for blood types A, B and C (AB) in purpose-bred cats

In domestic cats, the AB blood group system consists of the three types A, B and C (also called AB). Mismatches can cause acute hemolytic transfusion reactions and hemolysis of the newborn (neonatal isoerythrolysis, NI). As blood types B and C are inherited recessively to A, breeders need to know the genotype to predict blood types in offspring and avoid NI. Several CMAH variants have been described as being associated with the b and a^c alleles, and different genotyping schemes exist. Here, we genotyped 2145 cats with the original SNV panel, including SNVs c.142G>A and ∆-53, and our new scheme, with SNVs c.179G>T, c.268T>A and c.1322delT, to differentiate types A and B and added the SNV for the common a^c (c.364C>T). Based upon the new scheme, all samples were assigned the correct genotype. No discordances appeared for the A allele, and new breed-specific SNVs (c.179G>T, c.1322delT) for the b allele were discovered. Furthermore, the genotypes A/a^c (type A), a^c /a^c (C) and a^c /b (C) could be detected. We found the variant c.179G>T in additional breeds: Ragdoll, Siberian, Scottish Fold, Chartreux, Neva Masquerade, British Shorthair and Highlander. Also, the variant c.364C>T was detected in additional breeds: Bengal, British Shorthair, Maine Coon, and Scottish Fold. We conclude that our new SNV panel is superior in genotyping cats than the original SNV panel and assures correct assignments of types A, B and C to assist veterinary clinicians and breeders to recognize, confirm and avoid blood incompatibilities such as acute hemolytic transfusion reactions and NI.

Phenotype frequencies of blood group systems (Rh, Kell, Kidd, Duffy, MNS, P, Lewis, and Lutheran) in blood donors of south Gujarat, India

Background:

This is the first study on phenotype frequencies of various blood group systems in blood donors of south Gujarat, India using conventional tube technique.

Material and Methods:

A total of 115 “O” blood group donors from three different blood banks of south Gujarat were typed for D, C, c, E, e, K, Jk^a, Le^a, Le^b, P₁, M, and N antigens using monoclonal antisera and k, Kp^a, Kp^b, Fy^a,Fy^b, Jk^b, S,s, Lu^a, and Lu^b antigens were typed using polyclonal antisera employing Indirect Antiglobulin Test. Antigens and phenotype frequencies were expressed as percentages.

Results:

From the 115 blood donor samples used for extended antigen typing in the Rh system, e antigen was found in 100% donors, followed by D [84.35%], C [81.74%], c [56.32%], and E [21.74%] with DCe/DCe (R₁ R₁, 40.87%) as the most common phenotype. k was found to be positive in 100% of donors and no K+k- phenotype was found in Kell system. For Kidd and Duffy blood group system, Jk(a+b+) and Fy(a-b-) were the most common phenotypes with frequency of 52.17% and 48.69%, respectively. In the MNS system, 39.13% donors were typed as M+N+, 37.39% as M+N-, and 23.48% as M-N+. S+s+ was found in 24.35% of donors, S+s- in 8.69%, and S-s+ as the commonest amongst donors with 66.96%. No Lu(a+b+) or Lu(a+b-) phenotypes were detected in 115 donors typed for Lutheran antigens. A rare Lu(a-b-) phenotype was found in 2.61% donors.

Conclusion:

Data base for antigen frequency of various blood group systems in local donors help provide antigen negative compatible blood units to patients with multiple antibodies in order to formulate in-house red cells for antibody detection and identification and for preparing donor registry for rare blood groups.